Rename ant-dracula-theme → gtk-dracula-theme

[Ant-Dracula] has moved to [Dracula].

[Dracula]: https://draculatheme.com
[Ant-Dracula]: https://github.com/EliverLara/Ant-Dracula

Homepage: https://draculatheme.com/gtk
Repository: https://github.com/dracula/gtk